1. Field of the Invention
This invention relates to valves, and more particularly, to temperature sensor valves in an engine or engine-driven accessory for altering the pressure of a fluid in response to at least a partial loss of coolant or an over-temperature condition.
2. Description of the Prior Art
In the operation of internal combustion engines it is frequently desirable to provide protection means for automatically shutting off the engine or at least reducing its operating RPM to a safe level when certain conditions occur which would be detrimental to the engine or to an engine-driven accessory, such as an air compressor, hydraulic pump or transmission. To provide such protection, devices have been designed which are responsive to the temperature of the engine or accessory coolant. When the temperature of the coolant exceeds a predetermined value, these devices actuate an engine engine protection device such as a fuel shut-off valve which shuts off the fuel supply to the engine. A device of this type is disclosed in a patent issued to Goodwin (U.S. Pat. No. 3,302,143). However, devices such as these sense only the temperature of the engine coolant, whereas engine damage can occur when engine coolant is lost. Upon loss of engine coolant, the Goodwin apparatus will be ineffective since it will sense a low temperature because the coolant is no longer in contact with its temperature sensing probe. To protect an engine from damage due to loss of coolant a separate coolant level sensor must be provided to operate in conjunction with the Goodwin device to prevent damage due to an engine over-temperature condition resulting from loss of engine coolant. The requirement for a separate coolant temperature sensor and a coolant level sensor substantially increases the cost of installation of these devices since each device must be separately installed on the engine and coupled to a separate engine protection means for shutting down the engine when a loss of coolant occurs or when an engine over-temperature condition exists.
Other types of engine protection devices for preventing damage due to an engine over-temperature condition are disclosed in the following U.S. Pat. Nos. 3,153,403 (Dobbs), 2,125,066 (Cox), 1,869,429 (King), 1,838,409 (King).